The known electrolyzers of this type have adopted a construction that flat electrode plates are immersed in an electrolyzer so that both electrodes may be arranged in parallel to each other or a construction that both electrodes are formed in a cylindrical shape to be immersed in a cylindrical electrolyzer, as disclosed in Japanese Patent Application Laid-Open No. sho 61-241592 and Japanese Patent Application Laid-Open No. Sho 61-276986.
However, with such an electrode construction, a disadvantage has occurred in that an inner side opposite to a cathode in an anode surface can be charged to exhibit aimed characteristics by a processed article added in order to particularly improve a corrosion resistance of said anode surface but a complicated uneven charged condition is generated on a surface on the opposite side and thus an unnecessary measure for giving a corrosion resistance to a back side must be taken. In addition, a thermal expansion due to a heating of the anode frequently has led to a generation of a separation of a surface of a metal to be processed from an internal mother metal. In addition, it has been difficult to maintain a long-term operation at a high-charge and a necessary sectional area is required for an electric wire in order to avoid a heating in a supply of an increased electric current and thus said electric wire is thickened. Furthermore, an operating voltage is greatly influenced by a distance between the anode and the cathode and said voltage is reduced with a reduction of said distance so that it is preferable that the distance between the anode and the cathode is reduced as far as possible. However, it has been difficult to mutually meet the desired conditions in these known arts.
In general, in an electrolyzing operation, all of an electric current charged in the respective electrodes is not used for a movement of an aimed substance but is used for a decomposition of water on electrode surfaces proportional to a concentration of a free acid in the liquid in an increased ratio. In addition, said electrode surfaces are covered with bubbles of gaseous ingredients generated by this decomposition and an insulated bubble layer is formed in a radical case and thus the aimed electric current can not pass in many cases. Accordingly, an effective measure has been sought.
Furthermore, in general, the respective electrodes have been charged with a direct current always in an appointed direction without changing a charging polarity always.
However, in the case where an electric current having such the wave form is charged, said gaseous bubbles generated from a film surface are still more grown to be burst up, whereby giving a great shock to the electrode surfaces when burst up, oxidized particles of the metal being stuck in particular to the electrode surfaces. Thus, in the case where the electrodes have a construction that the electrode surfaces are protected, an influence by said construction is increased and a current density can not but being suppressed to one considerably lower than the aimed current density in order to reduce said influence in many cases.
Accordingly, it is a subject in this field how to make an effective device for maintaining a useful life time of the electrodes at an electric current charged of a value close to the usable current density of the electrodes.
In addition, since a coexisting of many kinds of ion in an acidic bath can not be avoided, results by an electrolytic separating operation in a liquid containing these kinds of ion are greatly different from those obtained by an operation in a liquid having a simple composition. In particular, in the case where an ion exchange resin exhibiting a high selectivity of passing kinds of ion is used, it has been thought that an almost perfect separation is possible but actually no satisfactory result has been obtained in the real industrial applied fields.